F-Secure subscription still valid but disappeared from my Mac

F-Secure subscription still valid but disappeared from my Mac

I have a subscription valid until mid-May 2019. Just before New Year I started getting warnings that the subscription was expiring. If I tried to renew it, the message was that I already had a valid subscription. See from other postings on the forum that reinstalling the program may work, as the original program may have accidentally been deleated in an update. How do I reinstall? And to the advice of releasing the lisence first, if I click that option the warning is the program will stop working - and do I want that? Someone with a good, step-by-step explanation here?